Generally, in a multi-carrier mobile communication system, a base station performs downlink data packet transmission to user equipments (hereinafter abbreviated UEs) belonging to a cell or each of a plurality of cells. Meanwhile, a plurality of UEs may exist within a cell. Since each of the UEs is unable to know how a data packet will be transmitted to itself using a prescribed format, when a base station transmits a downlink data packet to a specific UE, the base station should transmit such necessary information as an ID of a UE that will receive the corresponding data packet, a time-frequency domain for carrying the data packet, a data transmission format including a coding rate, a modulation scheme and the like, HARQ relevant information, and the like in downlink for each downlink data packet transmission.
On the contrary, in order to enable a UE to transmit a data packet in uplink, a base station should transmit such necessary information as an ID of a UE that will be approved for data packet transmission, an uplink time-frequency domain enabling the UE to transmit the data packet, a data transmission format including a coding rate, a modulation scheme and the like, HARQ relevant information, and the like in downlink for each uplink data packet transmission.
In case of the uplink data packet transmission, a base station should transmit reception success acknowledgement/non-acknowledgement (ACK/NACK) information on each data having been transmitted by a UE to the corresponding UE in uplink. On the other hand, in case of downlink data packet transmission, each UE transmits information about reception success or failure for each data packet having been transmitted by a base station through ACK/NACK information in uplink.
In order to maintain an uplink transmission/reception power of each UE at a proper level, a base station should transmit power control information to each UE in downlink.
Among the above-explained control signals, an ACK/NACK signal, a power control signal or the like is mainly able to indicate the corresponding information using one bit and can be named ‘1-bit control signal’.
In order to operate and manage a system efficiently, it is necessary to multiplex an uplink/downlink control signal for carrying the above-explained control information, and more particularly, the 1-bit control signal with a data packet and other signals in a time-frequency resource efficiently.
As a multiplexing scheme normally used for a multi-carrier mobile communication system, time division multiple access (TDMA) for multiplexing a plurality of signals by dividing them on a time domain, frequency division multiple access (FDMA) for multiplexing a plurality of signals by dividing them on a frequency domain, code division multiple access (CDMA) for multiplexing signals on a prescribed time-frequency domain using an orthogonal code or a pseudo-orthogonal code, or the like can be used.
Yet, in case that the 1-bit control signal is multiplexed using TDMA and/or FDMA only, since a transmission power of each control signal considerably differs, an effect on a neighbor cell may differ on a time domain and/or a frequency domain.
In particular, when a random cell multiplexes to transmit ACK/NACK signals for different UEs within a single TTI by TDMA or FDMA for example, in case that an ACK/NACK signal transmission power for each of the UEs considerably differs, a quantity of interference imposed on neighbor cells by the corresponding cell may differ considerably on a time domain or a frequency domain. And, this may have a bad influence on performing downlink data packet scheduling in a cellular environment or time-frequency-energy distributions efficiently.
Moreover, in case that a control signal such as an ACK/NACK signal of a transmitting side is lost in the course of downlink/uplink channel transmission, there may be a problem of reliability on the corresponding signal transmission.